Field of the Invention
The present application relates to various related polymers polymerized from at least one reactive vinyl monomer containing an acid functionality and at least one reactive vinyl monomer containing amide functionality. Compositions comprising such polymers may be used for gas hydrate inhibition and corrosion resistance.
Description of Related Art
It is known in oilfield operations that gas hydrates, also known as clathrate hydrates form under certain conditions in fluids having water and hydrate-forming molecules. The gas hydrate formation may lead to blockade of a wide variety of fluid transportation means such as pipelines, valves and production systems. In order to prevent this, gas hydrate inhibitors are added to the fluids.
Two types of inhibitors have been identified that inhibit gas hydrate formation, thermodynamic inhibitors and kinetic inhibitors. Both types are distinguished from hydrate anti-agglomerants, which prevent the hydrate crystals from agglomerating and accumulating into large masses.
Thermodynamic inhibitors shift the equilibrium hydrate dissociation/stability curve, i.e., the hydrate-aqueous liquid-vapor equilibrium (HLVE) curve, to a lower temperature and thus avoid the hydrate formation. Methanol is such an inhibitor that is quite effective and widely used. However, as exploration and production moves to deeper seas, temperature and pressure conditions in the field become in favor of hydrate formation, i.e., the temperature is colder and the pressure is higher, and the addition of this type of inhibitor can be expensive and environmentally prohibitive; the inhibitor concentration required to prevent hydrate formation is very high, often in excess of 60% (w/w). Sodium chloride is another example that has been used as a thermodynamic inhibitor. However, adding inorganic salts alone may lead to corrosion problems.
Kinetic inhibitors, on the other hand, do not prevent the hydrate formation at a certain condition, but retard the hydrate formation rate by slowing down the hydrate nucleation and growth rates. In deep sea gas exploration, an effective gas hydrate inhibitor delays the hydrate formation to a longer time than the residence time of the fluids in the hydrate-prone section of pipeline. Poly(N-vinyl-2-pyrrolidone) (PYP) is an example of a kinetic inhibitor.
A number of these gas hydrate inhibitors are described U.S. Pat. Nos. 3,629,101; 5,639,925; 6,177,497; and 6,194,622; and U.S. Patent Application Publication Nos. 2006/0058449 and 2007/0100102.
In addition to the problems posed by gas hydrates, corrosion can affect the extraction of hydrocarbons. Corrosion also impacts a multitude of other industries, such as electrical power generation, marine, chemical, and transportation. It is important for organizations to protect the essential structures from corrosion.
The existing gas hydrate inhibitors and corrosion inhibitors lack in their performance, especially for products having both gas hydrate inhibition and corrosion properties. Therefore, there is a need for better gas hydrate inhibitors and corrosion inhibitors.